Through the video Dr. Alexander L. Kholodov walks us through the process they use to calibrate their sensors.
First step is placing ice cubes and mixing distilled water in a common blender.
The blender is turned on then creates an ice mix (cold media)
The excess distilled water from the blender is poured back into its original pitcher.
The crushed ice mix is placed into a metal cylinder.
This process is repeated until the mix of ice nearly fills the metal cylinder. The excess distilled water is poured out of the metal cylinder into the water pitcher.
The cylinder holding the ice mix will now act as a standard reference of 0°C.
One Onset HOBO UX120 4-Channel Analog Logger is then prepared and its four sensors are placed into the cylinder of ice mix (cold media).
Dr. Alexander L. Kholodov then makes sure the sensors are working by cleaning any temperature sensor terminals of the data logger.
The four sensors of a data logger are inserted in the 0°C controlled metal chamber.
Using a laptop computer a USB cable is used to connect to the data logger.
After a short period of time using HOBO software, measurement is taken and an offset for each sensor is recorded.
The serial number of the data logger is recorded along with each of the four channel temperature readings from each logger in software.
During the video Offscreen Dr. Vladimir E. Romanovsky hands Dr. Alexander L. Kholodov a fast readout via direct USB interface Probe Temperature Data Logger.
We then see the Probe Temperature Data Logger placed in center of ice mix.
USB cable from laptop connects to the mini USB connection atop the Probe Temperature Data Logger.
Offset from 0°C is recorded to the Laptop and Probe Temperature Data Logger.
This process of checking data loggers, sensors and recording offsets with serial numbers of each Onset HOBO UX120 4-Channel Analog Loggers is repeated until all loggers and its four channel sensors have been individually calibrated and recorded in HOBO software.
Later in the video we see in his office Dr. Vladimir E. Romanovsky verifies with his laptop computer that the sensor for borehole temperature measurements has been successfully calibrated for his use in field work.
The calibration offsets for each of the four independent channels of all data loggers are ultimately archived and made available to researchers to accurately measure and record temperature through time with high precision in air and soil during their permafrost research across the globe in Alaska & Siberia.
About The Geophysical Institute Permafrost Laboratory
The Permafrost Laboratory deals with scientific questions related to circumpolar permafrost dynamics and feedbacks between permafrost and global change. At the Permafrost Laboratory, data related to the thermal and structural state of circumpolar permafrost is collected and analyzed. The focus of our research is development of methods to physically and mathematically model permafrost interactions with the climate system (permafrost modeling); study of naturally and human-induced disturbances of permafrost (permafrost process studies); detection of changes in permafrost temperature, thickness, and distribution over time (permafrost monitoring); and prediction of impacts of permafrost changes on the natural environment (e.g. ecosystems, hydrology, carbon cycle) as well as human-related concerns (e.g. infrastructure).
We are interested in all aspects of how permafrost is affected by global change with respect to climate as well as natural and human-induced disturbances. The Permafrost Lab was established in the 1960s by Professor Thomas E. Osterkamp at the Geophysical Institute of the University of Alaska Fairbanks.
Our team consists of Professor of Geophysics Vladimir Romanovsky, Associate Professor Dr. Sergey S. Marchenko, Assistant Professor Dr. Dmitry Nicolsky, Research Associates Dr. Alexander Kholodov, Dr. Reginald Muskett and Dr. Santosh Panda; doctoral students Viacheslav V. Garayshin, Louise Farquharson, and Prajna Regmi Lindgren.
Research Professional Lily Cohen and Research Professional II Bill Cable (also a Masters Graduate Student at the University of Copenhagen - University of The Arctic) complements our group with their expertise. We closely collaborate with many other researchers and students at UAF. Our collaborations extend to the Department of Energy Laboratories and the Department of Interior USGS, The Alfred Wegener Institute, The World Meteorological Organization and the International Permafrost Association and many universities in Europe, Russia and China.
Wikipedia describes calibration as:
is the process of finding a relationship between
two quantities that are unknown (when the measurable quantities are not
given a particular value for the amount considered or found a standard
for the quantity). When one of quantity is known, which is made or set
with one device, another measurement is made as similar way as possible
with the first device using a second device.The measurable quantities
may differ in two devices which are equivalent. The device with the
known or assigned correctness is called the standard. The second device is the unit under test, test instrument, or any of several other names for the device being calibrated.
The formal definition of calibration by the International Bureau of Weights and Measures
is the following: "Operation that, under specified conditions, in a
first step, establishes a relation between the quantity values with
measurement uncertainties provided by measurement standards and
corresponding indications with associated measurement uncertainties (of
the calibrated instrument or secondary standard) and, in a second step,
uses this information to establish a relation for obtaining a
measurement result from an indication."
Dr. Alexander L. Kholodov Research Associate Permafrost Lab, Geophysical Institute, University of Alaska, Fairbanks
Dr. Vladimir E. Romanovsky Professor of Geophysics, Permafrost Lab, Geophysical Institute, University of Alaska, Fairbanks
Paul Garrett Hugel Videographer/Editor/Publisher
Production of NKO.ORG in association with Maui Scientific Analysis & Visualization of The Environment Program
Shot on Location Permafrost Lab, Geophysical Institute, University of Alaska, Fairbanks
Special Thanks to everyone at Permafrost Lab, Geophysical Institute and The University of Alaska, Fairbanks
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